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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2012 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: AnnotatedXMLEventReader.html 813 2013-12-23 16:52:26Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.xml;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import javax.xml.stream.XMLEventReader;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import javax.xml.stream.XMLStreamException;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import javax.xml.stream.events.Comment;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import javax.xml.stream.events.XMLEvent;<a name="line.13"></a>
<span class="sourceLineNo">014</span>import javax.xml.stream.util.EventReaderDelegate;<a name="line.14"></a>
<span class="sourceLineNo">015</span><a name="line.15"></a>
<span class="sourceLineNo">016</span>/**<a name="line.16"></a>
<span class="sourceLineNo">017</span> * {@link XMLEventReader} that reads and removes an initial annotation element from an XML document.<a name="line.17"></a>
<span class="sourceLineNo">018</span> * The annotation element, if present, must be the first element inside the top-level document element.<a name="line.18"></a>
<span class="sourceLineNo">019</span> * {@link #readAnnotationElement readAnnotationElement()} must be provided by the subclass to determine<a name="line.19"></a>
<span class="sourceLineNo">020</span> * whether the first non-top element is the expected annotation element, and read it if so.<a name="line.20"></a>
<span class="sourceLineNo">021</span> * Whoever reads from this {@link AnnotatedXMLEventReader} instance class will not see the annotation element.<a name="line.21"></a>
<span class="sourceLineNo">022</span> *<a name="line.22"></a>
<span class="sourceLineNo">023</span> * &lt;p&gt;<a name="line.23"></a>
<span class="sourceLineNo">024</span> * This class can be used in combination with {@link AnnotatedXMLEventWriter} to transparently annotate XML documents.<a name="line.24"></a>
<span class="sourceLineNo">025</span> * &lt;/p&gt;<a name="line.25"></a>
<span class="sourceLineNo">026</span> *<a name="line.26"></a>
<span class="sourceLineNo">027</span> * @see AnnotatedXMLEventWriter<a name="line.27"></a>
<span class="sourceLineNo">028</span> */<a name="line.28"></a>
<span class="sourceLineNo">029</span>public abstract class AnnotatedXMLEventReader extends EventReaderDelegate {<a name="line.29"></a>
<span class="sourceLineNo">030</span><a name="line.30"></a>
<span class="sourceLineNo">031</span>    // State:<a name="line.31"></a>
<span class="sourceLineNo">032</span>    //  0 = before document element<a name="line.32"></a>
<span class="sourceLineNo">033</span>    //  1 = after document element but before annotation element (if any)<a name="line.33"></a>
<span class="sourceLineNo">034</span>    //  2 = after annotation element (if any)<a name="line.34"></a>
<span class="sourceLineNo">035</span>    private byte state;<a name="line.35"></a>
<span class="sourceLineNo">036</span><a name="line.36"></a>
<span class="sourceLineNo">037</span>    /**<a name="line.37"></a>
<span class="sourceLineNo">038</span>     * Constructor.<a name="line.38"></a>
<span class="sourceLineNo">039</span>     *<a name="line.39"></a>
<span class="sourceLineNo">040</span>     * @param parent parent reader<a name="line.40"></a>
<span class="sourceLineNo">041</span>     */<a name="line.41"></a>
<span class="sourceLineNo">042</span>    public AnnotatedXMLEventReader(XMLEventReader parent) {<a name="line.42"></a>
<span class="sourceLineNo">043</span>        super(parent);<a name="line.43"></a>
<span class="sourceLineNo">044</span>    }<a name="line.44"></a>
<span class="sourceLineNo">045</span><a name="line.45"></a>
<span class="sourceLineNo">046</span>    @Override<a name="line.46"></a>
<span class="sourceLineNo">047</span>    public Object next() {<a name="line.47"></a>
<span class="sourceLineNo">048</span>        try {<a name="line.48"></a>
<span class="sourceLineNo">049</span>            return this.nextEvent();<a name="line.49"></a>
<span class="sourceLineNo">050</span>        } catch (XMLStreamException e) {<a name="line.50"></a>
<span class="sourceLineNo">051</span>            throw new RuntimeException(e);<a name="line.51"></a>
<span class="sourceLineNo">052</span>        }<a name="line.52"></a>
<span class="sourceLineNo">053</span>    }<a name="line.53"></a>
<span class="sourceLineNo">054</span><a name="line.54"></a>
<span class="sourceLineNo">055</span>    @Override<a name="line.55"></a>
<span class="sourceLineNo">056</span>    public XMLEvent peek() throws XMLStreamException {<a name="line.56"></a>
<span class="sourceLineNo">057</span>        XMLEvent event = super.peek();<a name="line.57"></a>
<span class="sourceLineNo">058</span>        if (this.state == 1)<a name="line.58"></a>
<span class="sourceLineNo">059</span>            event = this.checkAnnotation(event);<a name="line.59"></a>
<span class="sourceLineNo">060</span>        return event;<a name="line.60"></a>
<span class="sourceLineNo">061</span>    }<a name="line.61"></a>
<span class="sourceLineNo">062</span><a name="line.62"></a>
<span class="sourceLineNo">063</span>    @Override<a name="line.63"></a>
<span class="sourceLineNo">064</span>    public XMLEvent nextEvent() throws XMLStreamException {<a name="line.64"></a>
<span class="sourceLineNo">065</span>        switch (this.state) {<a name="line.65"></a>
<span class="sourceLineNo">066</span>        case 0:<a name="line.66"></a>
<span class="sourceLineNo">067</span>            XMLEvent event = super.nextEvent();<a name="line.67"></a>
<span class="sourceLineNo">068</span>            if (event.isStartElement())<a name="line.68"></a>
<span class="sourceLineNo">069</span>                this.state++;<a name="line.69"></a>
<span class="sourceLineNo">070</span>            return event;<a name="line.70"></a>
<span class="sourceLineNo">071</span>        case 1:<a name="line.71"></a>
<span class="sourceLineNo">072</span>            this.peek();<a name="line.72"></a>
<span class="sourceLineNo">073</span>            return super.nextEvent();<a name="line.73"></a>
<span class="sourceLineNo">074</span>        default:<a name="line.74"></a>
<span class="sourceLineNo">075</span>            return super.nextEvent();<a name="line.75"></a>
<span class="sourceLineNo">076</span>        }<a name="line.76"></a>
<span class="sourceLineNo">077</span>    }<a name="line.77"></a>
<span class="sourceLineNo">078</span><a name="line.78"></a>
<span class="sourceLineNo">079</span>    /**<a name="line.79"></a>
<span class="sourceLineNo">080</span>     * Determine if the next event from the given {@link XMLEventReader} is the annotation element, and if so, read it.<a name="line.80"></a>
<span class="sourceLineNo">081</span>     *<a name="line.81"></a>
<span class="sourceLineNo">082</span>     * &lt;p&gt;<a name="line.82"></a>
<span class="sourceLineNo">083</span>     * This method should invoke {@link #peek reader.peek()} to determine if the next event is the annotation<a name="line.83"></a>
<span class="sourceLineNo">084</span>     * {@link javax.xml.stream.events.StartElement}; if it's not, this method should not read any events and immediately<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * return false. Otherwise, it should read the annotation {@link javax.xml.stream.events.StartElement} and all<a name="line.85"></a>
<span class="sourceLineNo">086</span>     * subsequent events up &lt;i&gt;through&lt;/i&gt; the matching {@link javax.xml.stream.events.EndElement} and return true.<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * &lt;/p&gt;<a name="line.87"></a>
<span class="sourceLineNo">088</span>     *<a name="line.88"></a>
<span class="sourceLineNo">089</span>     * @param reader source from which the rest of the annotation element is to be read<a name="line.89"></a>
<span class="sourceLineNo">090</span>     * @return false if the annotation element is not seen, true if seen and fully read<a name="line.90"></a>
<span class="sourceLineNo">091</span>     */<a name="line.91"></a>
<span class="sourceLineNo">092</span>    protected abstract boolean readAnnotationElement(XMLEventReader reader) throws XMLStreamException;<a name="line.92"></a>
<span class="sourceLineNo">093</span><a name="line.93"></a>
<span class="sourceLineNo">094</span>    /**<a name="line.94"></a>
<span class="sourceLineNo">095</span>     * Scan for the annotation. We only allow whitespace and comments between the first {@link StartElement} and the<a name="line.95"></a>
<span class="sourceLineNo">096</span>     * annotation {@link StartElement}. Whitespace after the annotation {@link javax.xml.stream.events.EndElement} is removed.<a name="line.96"></a>
<span class="sourceLineNo">097</span>     *<a name="line.97"></a>
<span class="sourceLineNo">098</span>     * Pre-condition:<a name="line.98"></a>
<span class="sourceLineNo">099</span>     *  - Given event comes after the document element and is before or equal to updates start element<a name="line.99"></a>
<span class="sourceLineNo">100</span>     *  - Given event is the current "peek event" for this stream<a name="line.100"></a>
<span class="sourceLineNo">101</span>     *<a name="line.101"></a>
<span class="sourceLineNo">102</span>     * Post-condition:<a name="line.102"></a>
<span class="sourceLineNo">103</span>     *  - If event was updates start element, updates were consumed, else no change<a name="line.103"></a>
<span class="sourceLineNo">104</span>     *  - If updates were consumed:<a name="line.104"></a>
<span class="sourceLineNo">105</span>     *      - New "peek event" is whatever follows updates and trailing whitespace<a name="line.105"></a>
<span class="sourceLineNo">106</span>     *      - State has advanced<a name="line.106"></a>
<span class="sourceLineNo">107</span>     *  - Returned event is the (possibly new) "peek event"<a name="line.107"></a>
<span class="sourceLineNo">108</span>     */<a name="line.108"></a>
<span class="sourceLineNo">109</span>    private XMLEvent checkAnnotation(XMLEvent event) throws XMLStreamException {<a name="line.109"></a>
<span class="sourceLineNo">110</span><a name="line.110"></a>
<span class="sourceLineNo">111</span>        // Sanity check<a name="line.111"></a>
<span class="sourceLineNo">112</span>        assert this.state == 1;<a name="line.112"></a>
<span class="sourceLineNo">113</span><a name="line.113"></a>
<span class="sourceLineNo">114</span>        // Ignore leading whitespace, comments, and PI's<a name="line.114"></a>
<span class="sourceLineNo">115</span>        if (this.isWhiteSpace(event) || event instanceof Comment || event.isProcessingInstruction())<a name="line.115"></a>
<span class="sourceLineNo">116</span>            return event;<a name="line.116"></a>
<span class="sourceLineNo">117</span><a name="line.117"></a>
<span class="sourceLineNo">118</span>        // Anything else means we either we have found the annotation element or it is not there<a name="line.118"></a>
<span class="sourceLineNo">119</span>        this.state++;<a name="line.119"></a>
<span class="sourceLineNo">120</span>        if (!event.isStartElement() || !this.readAnnotationElement(this.getParent()))<a name="line.120"></a>
<span class="sourceLineNo">121</span>            return event;<a name="line.121"></a>
<span class="sourceLineNo">122</span><a name="line.122"></a>
<span class="sourceLineNo">123</span>        // Skip whitespace after annotation element<a name="line.123"></a>
<span class="sourceLineNo">124</span>        for (event = super.peek(); this.isWhiteSpace(event); event = super.peek())<a name="line.124"></a>
<span class="sourceLineNo">125</span>            super.nextEvent();<a name="line.125"></a>
<span class="sourceLineNo">126</span><a name="line.126"></a>
<span class="sourceLineNo">127</span>        // Done<a name="line.127"></a>
<span class="sourceLineNo">128</span>        return event;<a name="line.128"></a>
<span class="sourceLineNo">129</span>    }<a name="line.129"></a>
<span class="sourceLineNo">130</span><a name="line.130"></a>
<span class="sourceLineNo">131</span>    private boolean isWhiteSpace(XMLEvent event) {<a name="line.131"></a>
<span class="sourceLineNo">132</span>        return event.isCharacters() &amp;&amp; event.asCharacters().isWhiteSpace();<a name="line.132"></a>
<span class="sourceLineNo">133</span>    }<a name="line.133"></a>
<span class="sourceLineNo">134</span>}<a name="line.134"></a>
<span class="sourceLineNo">135</span><a name="line.135"></a>




























































</pre>
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